High density optical recording systems which may be used for recording and playing back information are known in the prior art. For example, U.S. Pat. No. 4,097,895, entitled "MULTI-LAYER OPTICAL RECORD" issued on June 27, 1978, in the name of F. W. Spong relates to an optical disc record/playback system wherein data is recorded on the surface of a recording medium. In a Spong system the thermal energy of a focused high intensity light beam causes variations of the optical properties on the surface of the recording medium, for example, in one system the thermal effects of a laser beam form pits in an absorptive coating on the surface of an optical disc. In the Spong system, approximately 10.sup.11 bits of information can be recorded on one side of a disc-shaped record medium having a 30 centimeter diameter.
In some optical recording systems, it is desirable to provide a mass memory system in which any data in a store of approximately 10.sup.13 bits, i.e., 100 record media, could be automatically accessed in a few moments. In one system a library of several record media are stored in a storage bin of an optical mass memory system. A mechanism is used for transferring a selected disc from the storage bin to a read/write station where the information may be processed. Such mechanisms must be capable of automatically selecting the correct disc, automatically handling the disc into and out of the read/write station and automatically returning the disc to a storage location after processing is complete. Automatic handling of this type must be accomplished reliably and accurately to be able to access the data at a high rate of speed.